This invention relates to the control of a missile, and, more particularly, to a control surface positioned for improved effectiveness.
The trajectory of missiles that fly through the air can be controlled either by moving control surfaces into the air stream, pivoting the primary propulsion engine, pushing the nose of the missile sideways with thrusters, or a combination of these techniques. Movable control surfaces are preferred for many applications, because the are effective and well understood, and because their added weight is relatively small. The present invention is concerned with the control of missile flight with movable control surfaces.
Movable control surfaces may be provided on the wings of the missile, if any, or extending from the body of the missile. In the latter case, a trailing edge body flap typically is found on a wingless missile carried in an internal weapons bay of an aircraft. This type of missile relies primarily on the power of its engine rather than aerodynamic lift to maintain it aloft. There are typically four body flaps, symmetrically located 90 degrees apart around the tail of the missile. Each body flap is a panel that is pivotable outwardly from a position flush with the body of the missile to a position in which it extends into the air stream. The body flaps do not provide primary lift to the missile. Instead, the unbalanced aerodynamic effect of the extended flap is used to change the orientation of the missile and thence control its direction of flight. The flaps are used singly or in combination to attain the selected flight orientation.
It has been observed that such controllable body flaps often experience reduced effectiveness as the speed of the missile increases into the high subsonic, transonic, and supersonic speed ranges, and at high altitudes. The result is reduced sensitivity of the missile to its control commands, and the need to use larger flaps to maintain a required level of sensitivity at high speeds and altitudes.
There is a need for an improved control approach for missiles that reduces the degradation of control effectiveness. The present invention fulfills this need, and further provides related advantages.